Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
hanh vai » hanh vi, hanh va, hanh van
hanh tai » thanh tai, hang tai, han tai
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
ve bac » ve bao, ve cac, ve ban
bo van » vo van, so van, do van
x hoi » o hoi, x ho, 5 hoi

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ky nang ((x hoi) or (xa hoi)). hieu ve bac bo van ((hanh vai) OR (hanh tai)) cua triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((x hoi) OR (xa hoi)). hieu ve bac bo van ((hanh vai) OR (hanh tai)) cua triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ((x hoi) or (xa hoi)). hieu ve bac bo van ((hanh vai) OR (hanh tai)) cua triet".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((x hoi) or (xa hoi)). hieu ve bac bo van ((hanh vai) OR (hanh tai)) cua triet*.